Opponents of genetically modified organisms — known as GMOs — gathered across the nation and the world Saturday to protest the Monsanto Co.

The March Against Monsanto targeted the biotech corporation’s effect on global agriculture and food safety.

Monsanto produces genetically engineered seeds and the herbicide Roundup, which critics say is contaminating the nation’s food supply. Some critics also say Monsanto wields enough political influence to stifle laws and research on the health effects of GMOs, which are banned in several countries.

About 150 people participated in Saturday’s event in Olympia, which started with a rally on the Capitol Campus, then ended with a sign-waving march along Capitol Way toward the Olympia Farmers Market.

Several people at Saturday’s march said they joined the GMO fight after the recent failure of Initiative 522, which would have required labels for genetically engineered foods in Washington. Lacey resident Jennie BGreen said she hopes Saturday’s protests can increase pressure on food companies to change their policies and raise awareness of the health effects of GMOs.

“It made me think twice about what I was feeding my kid,” said BGreen, who also helped organize last year’s local March Against Monsanto.

Rainier resident Michael Savoca wants more accountability when it comes to testing the long-term safety of genetically engineered foods.

“The test is being done, and it’s being done on you and me,” said Savoca, an independent candidate in District 20 for the state House of Representatives. “There is a symphony of chemicals that are inundating our systems.”

Tacoma resident Nanette Reetz attended Saturday’s march on behalf of Moms Across America Pierce County, an anti-GMO advocacy group. Reetz said she will travel this week to Washington, D.C., to lobby the Environmental Protection Agency to revise its requirements for GMO-related safety studies.

“We’re concerned that the data is compromised,” said Reetz, citing studies that suggest GMOs are linked to a rise in autism and other conditions. “We have testimony after testimony from moms where their kids’ health improved when GMOs were removed.”

On its website, Monsanto addresses criticisms about the company.

“While opponents of GMO crops often describe them as ‘untested’ or ‘unsafe,’ this is simply not true,” the company reports. “We place the highest priority on the safety of our products.”

The company acknowledges lobbying for laws and regulations in its industry, but denies having “undue influence on governments.” The company also denies suing farmers when Monsanto’s seeds accidentally end up in their fields — an anecdote that was circulating among Saturday’s protesters in Olympia.

Corporate Responsibility Magazine has ranked Monsanto at No. 38 in its 100 Best Corporate Citizens of 2014.

On the other side, residents in Jackson and Josephine counties in southern Oregon recently voted to ban genetically engineered crops and seeds. Monsanto donated to the opposition campaign in Jackson County, according to The Oregonian.

In response to the ban, Oregon Farm Bureau President Barry Bushue was quoted as saying, “ideology defeated sound science and common sense.”